(A) Intramolecular cross-links of Atg18 are shown with red lines. Cross-links that are not included in the crystal structure are indicated by dotted lines. The seven blades of the β-propeller are rainbow colored. Residues missing from the crystal structure are highlighted in grey and light orange (residues 297–437, blade 6). (B) Bar diagramme indicating intermolecular Atg18 interactions (blue Lines). (C) Native mass spectrum of Atg18 oligomers. Calculated masses of the oligomers are given. (D) Intramolecular cross-links identified in Atg18 in the presence of liposomes. (E) Blue lines indicate intermolecular cross-links between two Atg18 molecules in the presence of liposomes. Red lines show protein-PE cross-links. PE cross-linked residues are labelled.